Low-temperature bright-annealing



April 25, 1933. R. J. cowAN ET AL, I 9

. LOW TEMPERATURE BRIGHT ANNEALING Filed Dec. 29, 1930 uvvavroms:

R d. C OM fi/V 0. 5., CULL E/V HTTOIF/VEY.

. minimum temperature of 1300 cleaning agent.

Patented Apr. 25,- 1933 UNITED STATES PATENT, OFFICE J OHIO, ASSIGNORS TO SURFACE A. CORPORATION OF NEW YORK LOW-TEMPERATURE BRIGHT-HEALING Application filed December 29, 1930. Serial No. 805,240.

This invention relates to the art of brightannealing metals andhas; for its object to provide a process wherein. hydrogen or a hydrogen-bearing as may be used as the Nfore particularly it is an object of the invention to provide a process for the bright-annealing of metals that must be heat-treated at relatively-low temperatures, for example at temperatures between 800 and 1200911.

Conspicuous among the metals which must be annealed between the temperatures indicated is bra'ss. So-called bright-annealing of this metal has at the best produced no more than ajlack-lustre finish irrespective of the cleaning gas employed.

We have discovered that brass and other metals which must be annealed at relative] low temperature can be given a lustrous finis during the'annealing operation by subjecting the metal to the action of hydrogen or a hydrogen-bearing gas provided the hydrogen or said gas is heated above a certain minimum critical temperature of 1200 F. With an iron (steel) or a chromium-nickel reaction chamber, the minimum temperature is 1200- F but in practicalo oration a is found most suitable. Hydrogen or a hydrogenbearing gas heated above said minimum temperature we term activated hydrogen. For

-convenience of description, hydrogen and hydrogen-bearing gas before such heating will be called raw gas.

The manner of activating'theraw gas as said and at the same time preventing the metal from being over-heated is substantially as follows: The reaction chamber is maintained at a temperature above 1200 erably above 1300 F. The raw gas is admitted into this reaction chamber, the gas beingpreferably first preheated. The metal is then passed through the reaction chamber at such a speed that the desired annealin temperature will be attained but not exceed It is of course important that after being brought to annealing temperature the metal be cooled before being brought into contact with the open air. To this end, the metalis passed through a cooling chamber wherein F. prefan atmosphere consisting of spent activated gas may be maintained. In practical o eration, the reaction chamber and cooling 0 amber form onecontinuous tube the reaction chamber being contained within a furnace the temperature of trolled.

Preheating of the raw gas is preferably efi'ected by abstractionof heat from the cooling chamber. To this end, the raw gas is passed through a conduit contained within which may be readily conthe cooling chamber, this\conduit terminating within the reaction chamber. We have referred to a hy hydrogen-bearing gases which have been successfully used are ethane, methane, propane, butane, ethylene and ammonia. The hydrogen liberated by these gases at the said mini mum temperature will-give the desired result. Of the various hydrogen-bearing gases mentioned, propane is preferred since it is a relatively cheap. substance.

' For a more complete understanding of the invention, reference is made to the detailed description taken in connection with the ac- In the drawing, 5 indicates any suitable heating furnace, the same being shown as provided with upper and-lower tiers of gas urners 6. Extending through the furnace isa inuflle 7. Formed as a continuation of the muflle is a cooling chamber 8. The mufiie and cooling chamber therefore constitute an elongated tube through which the'worklis to be passed. The work is indicated at W and as shown is in strand form, which is.

to be understood as being representative of wire and strip, the invention being particularly well adapted for bright annealing I drogen-bearinggas as well as hydrogen as such. Among thecompanying drawing, wherein the preferred strand material. Said tube is closed at both 5 ends 9 and 10 except for an inlet and outlet catalytic efiect on steel, chromium-nickelalloys.have such cf- 35 feet the and that lower critical tem charge for the work as will be readily understood. At each end of the tube is a valve controlled vent indicated at 11 and 12. As a means for assisting in cooling the cooling chamber 8 there is indicated a water spray 13.

14 indicates a pipe leading from a suppl of hydrogen or hydrogen-bearin gas. t is preferred that the raw gas be pre eated before being introduced into the mufile or reaction chamber -7 and to this end there is placed within the cooling chamber a partition 15 which divides the cooling chamber into upper and lower sections or assages, the raw as being introduced into t e lower 15 passage or flow into'the mufiie. Since it is to the inlet end of the muflle but in such event the extended partition should be perforated to rmit free escape of the heated gas.

he work is passed through the heattreating tube (mufile 7 and cooling chamber I 8) by any preferred reeling and unreeling mechanism, not shown. The muflle is preferably made of a substance which has a the hydrogen. Iron and latter material being preferred because of its heat resisting properties. -While the minimum temperature for activating the hydrogen may be as low as 1200 F. it is pre.- ferred to employ a higher temperature in order to more quickl heat the work. Inorder to prevent over eating of the work, it is plassed through theheat-treatin tube at sue a rate that the desired annea ing tem+ perature will not be exceeded. Practically speaking, there is no upper critical temperattire-beyond which the ydrogen must not be heated. There is, however, a lower critical temperature below which the hydrogen will not be activated for the purpose in view, rature is 1200 F., as already stated. For right-annealing brass, the preferred-temperature within the mufile is 1300 F. v

Before the work is passed through the heat.-

w treating tube, the latter must be thoroughly purged of the heated tube throng the vents at either end thereof. In 'normal'operation, the vent 12 at the disend of the cooling, chamber will be so restricted that .but little gas from the mufle will flow into the cooling chamber of its own accord, it bein important that most of the gas flow towa s the incomin work.

air. This is efiected by allowing To this end, the vent at the inlet en of the to flow from both ends of the mufile will be relatively unrestricted and the I gas admitted into the mufile will be under suitable pressure. a

Due to the relatively high temperature differential between the reaction chamber or mufile and the work, the latter is passed through the mufiie at relatively high speed especially when the work i the work may be passed throng the reaction relatively thin. strip or small size wire. The speed at which chamber is immaterial insofar as the cleanthe activated hydrogen is concerned, since its effect on the heated work is 1 immediate.

understood that the active cleaning agent is hydrogen and that insofar as the present in-- vention is concerned it is immaterial whether the hydrogen be in a commercially ure state or whether it be produced as a resu t of thermal decomposition of a gas'containing hydrogen in chemical combination.

While the invention is From the foregoing description it will be articularly well adapted to the continuous right annealing of strand material such as wire and strip,

nevertheless it is also applicable to the bright anneal" of metals requiring aconveyor to ca'W it t rough the heat treating tube.

hat we claim is: 1. In a method ofpreventing the forma-.

'tion of and removin surface tarnish on non-- are to be heat-treated ferrous metals whic at temperatures not substantially in excess of 1200? F-., the steps comprising continuously passing a gas containing hydrogen through a heating chamber maintained at a temperature substantially in excess of 1200' F-., movmg the metal throu such a rate that the desired heat-treating temperature will not be exceeded, continuing the movement of the metal through a coolin chamber, and continuously passing throug 1 the cooling chamber in the same direction of flow as the metal some of the gases from the heating chamber.

2. In a'method of preventing the formation of and removin surface tarnish on non ferrous metals whic require to be annealed at temperatures not in excess of 1200 F., the steps comprising continuously passing a gas containing hydrogen through a heating chamber maintained above 1200? F., passing the metalthrough said chamberyin a direction opposite to the flow of: said gas and at such rate' that the desiredannealing temperature will not be exceeded, continuing the movement of the metal through acooling chamber, and continuously passing through the cooling chamber-in the same-direction of flow as the metal some of the gases from the heatingchamber.

3. -In a method of removing surface tarnish or oxide on non-ferrous. metals while in a heatedcondition, the steps comprising heath said chamber in a dipp site to t e flow of the gas and at a gas containing hydrogen at a temperature in excess of 1200 F.

In testimony whereof we aflixiour signatures.

mal decomposition with the liberation of hy- 1 drogen above 1200 F. 4.-In a method of removing surface tarnish or oxide on non-ferrous metals while in a heated condition, the steps comprising heating the metal by moving it through an elongated heating chamber, initially heating a hydrogen gas out of contact with the metal to a temperature substantially the same as that of said chamber, continuously introduc- I ing the heated gas into said chamber intermediate the ends thereof, the temperature of said chamber being-maintained above 1200 F. and the gas beingcapable of thermal decomposition with the liberation of hydrogen above 1200 F., and transferring the metal from said chamber to a cooling zone whereinto the gases from the heating chamber are free to flow. Y

5. In a method of removing surface tarnish or oxide on non-ferrous metals while in a heated condition, the steps comprising heating the metal by passing it through an elongated heating chamber, continuously introducing a heated gas into said chamber at a p *5 point intermediate the ends of said chamber,

said gas containing free hydrogen gas, the l.-

heating chamber being maintained above 1200 F.

6. In a method of removing surface tarnish or oxide on non-ferrous metals while in a heated condition, the steps comprising heating the metal by passing it through an elongated heating chamber, continuously intro ducing a heated gas into said chamber at a point intermediate the ends of said chamber,

the heating chamber being maintained above- 1200 F., and the said gas being ammonia.

7. In a method of removing surface tarnish or oxide on non-ferrous metals while in a heated condition, the steps comprising heating the metal by passing it through an elongated heating chamber, continuously introducinga heated gas into said chamber at a point intermediate the ends of said chamber,

and causing the gas-to divide and flo'w the major portion towards the work inlet end of v the chamber and the minor portion towards the work .outlet end of said chamber, the- 50 heating chamber being maintained above 1200 F., and the gas containing hydrogen.

7 8. In a method of removing surface tarnish on metal articles while at a temperature ranging from 800 to 1200' the step c0m-' c5 prising flowingin. contact withfsaid articles 'ROYSEL J. COWAN. YORVILLE E. OULLEN.

CERTIEICATE 0F commotion;

mm No. 1,905,810. April 25. 1933.

Q I ROYSEL J. comm, in AL. f

It is-herebycertified that error appears in the printed specification of the above nnmberedpatent requiring correction as follows: Page 1, line 24, strike out the words "of l-200F"; page 3, lines 3 and l7, claims 3. and 4, respectively,

I for"'hydrogen" read "hydrocarbon": line 36, claim 5, for-"gas" second occurrence, rm "and"; and line 61, claim 7, before "gas" insert the word "said"; and that the said Letters Patent should be read with; these corrections therein that'thesame may conform to the record of the case in the Patent Office.

'- Signed and sealed this 23rd day of May, A. D. 1933.

ML 1 loom (Seel) Acting Commissioner of Patents.- 

